West German Offenlegungsschrift No. 3,039,422 shows a bearing having a plastic jacket including a radially directed portion forming a sealing lip adapted to engage the inner ring. While this seal is generally satisfactory from a functional viewpoint and does not present serious difficulties in assembling the ball bearing since the sealing lip contacts essentially a radial surface of the inner ring, it is noted, however, that when the contact surface of the inner ring is a cylindrical surface, during the assembly process, the seal must first be pushed over the edge area of the inner ring before it can assume its proper sealing position. It has been observed that during assembly in this fasion, the ring lip suffers considerable damage which means that the desired sealing effect is impaired at the time of assembly. The damage is accentuated and can be even greater, for example, when the inner ring raceway is on a shaft and when assembly requires that the seal be pushed over a rather long cylindrical section of the shaft. Shafts are often stepped down in diameter, having only coarsely machined cylindrical sections that are provided with annular grooves. In these instances, it it possible to effect satisfactory assembly only by the expenditure of additional effort while the risk of damaged seals must simply be accepted.
In another prior art design of the type shown in West German Registered Design No. 71-10,331, the sealing element is provided with annular grooves which provide a degree of radial elasticity. The entire seal, however, is guided in a housing part provided with a groove. It has been observed that the ring sealing lip becomes damaged when it is assembled in the manner described above.